CVE-2019-18678

moderate-risk
Published 2019-11-26

An issue was discovered in Squid 3.x and 4.x through 4.8. It allows attackers to smuggle HTTP requests through frontend software to a Squid instance that splits the HTTP Request pipeline differently. The resulting Response messages corrupt caches (between a client and Squid) with attacker-controlled content at arbitrary URLs. Effects are isolated to software between the attacker client and Squid. There are no effects on Squid itself, nor on any upstream servers. The issue is related to a request header containing whitespace between a header name and a colon.

Do I need to act?

~
10.0% chance of exploitation in next 30 days
EPSS score — moderate exploit probability
-
Not on CISA KEV list
No confirmed active exploitation reported to CISA
?
Patch status unknown
Check vendor advisories for fix availability and mitigation guidance
5
CVSS 5.3/10 Medium
NETWORK / LOW complexity
46
/ 100
moderate-risk
Severity 21/34 · High
Exploitability 11/34 · Low
Exposure 14/34 · Moderate